The present invention relates to the general field of making force transfer parts that are to be stressed in traction and in compression, which parts include a lug at at least one of their ends that is made of composite material and that is to receive a pin for providing a pivot connection with another part.
A non-limiting example of an application of the invention is that of making landing gear side-braces.
A landing gear side-brace serves to take up lateral forces exerted on the landing gear and to keep it in a deployed position after making contact with the ground. Typically, a side-brace comprises two arms that are hinged to each other and to the other parts of the landing gear at their ends, via pivot connections.
Such force transfer parts are subjected to large mechanical forces in operation, which forces are mainly in compression and in traction, and are oriented along the longitudinal axis of the part (i.e. the axis passing via the two ends of the part).
When such force transfer parts are made of composite material, they are exposed more particularly to several modes of failure, including crushing. In the event of high loading, the pin of the pivot connection generally tends to bend, thereby causing stress to be concentrated at the edges of the bore in the lug through which the pin passes, and such stress concentrations are particularly harmful for the composite material. Such local stress concentrations lead to transverse shear in the composite material, thereby initiating damage by delamination of the material, which can lead to it breaking.
The ability to withstand crushing in such force transfer parts thus becomes a feature that is particularly important in determining their dimensions, thereby limiting the possibilities of using composite materials for making such parts.